Zero suppression circuits in high speed numeric printing

ABSTRACT

A circuit for selectively suppressing the printing of nonsignificant zeros by a high speed printer which prints numeric characters in successive columns of decreasing significance by individually operating selected print hammers. The circuit includes a plurality of print suppressing circuits, each of which is associated with one of the columns and adapted to inhibit operation of the hammer in its associated column when a nonsignificant zero is to be printed there. When actuated, each print suppressing circuit also feeds a signal to the print suppressing circuit associated with the next least significant column to condition it to inhibit printing of any zeros in the next least significant column since any such zeros will be nonsignificant. A switch is associated with each column to inhibit its associated print suppressing circuit and, thereby, inhibit zero suppression in the column. However, each switch, when closed, also passes a signal to the print suppressing circuit associated with the next least significant column, conditioning it to inhibit printing of any zeros in its associated column. This starts a new zero suppression field in the next least significant column. Of course, the suppression of nonsignificant zeros in this column may also be inhibited by closing the switch associated with the column.

United States Patent [72] Inventor Louk G. Omflti Philadelphia, Pa. [21] Appl. No. 884,854 [22] Filed Dec., 1969 [45] Patented Sept. 7, 1971 [73] Assignee Mohawk Data Sciences Corporation Herkimer, N.Y.

[54] ZERO SUPPRESSION CIRCUITS IN HIGH SPEED NUMERIC PRINTING 4 Claims, 4 Drawing Figs.

[52] [1.8. CI 101/93 C,

' 307/38 [51] lnt.Cl B4lj9/l0 [50] FieIdotSearch 101/93 C,

93 MN, 93 R; 235/619, 1,6028; 307/38, 115

[56] References Cited UNITED STATES PATENTS 3,064,561 11/1962 Mauduit 101/93 C 3,139,818 7/1964 Koehn..... l01/93C 3,423,641 1/1969 Von Feldt.... 317/137 3,442,206 5/1969 Sugimoto 101/93 C 3,467,005 9/1969 101/93 C Pn'mary Examinerwilliam B. Penn Attorneys-Francis J. Thomas, Richard H. Smith, Thomas C. Siekman and Sughrue, Rothwell, Mion, Zinn and Macpeak ABSTRACT: A circuit for selectively suppressing the printing of nonsignificant zeros by a high speed printer which prints numeric characters in successive columns of decreasing significance by individually operating selected print hammers. The circuit includes a plurality of print suppressing circuits, each of which is associated with one of the columns and adapted to inhibit operation of the hammer in its associated column when a nonsignificant zero is to be printed there. When actuated, each print suppressing circuit also feeds a signal to the print suppressing circuit associated with the next least significant column to condition it to inhibit printing of any zeros in the next least significant column since any such zeros will be nonsignificant. A switch is associated with each column to inhibit its associated print suppressing circuit and, thereby, inhibit zero suppression in the column. However, each switch, when closed, also passes a signal to the print suppressing circuit associated with the next least significant column, conditioning it to inhibit printing of any zeros in its associated column. This starts a new zero suppression field in the next least significant column. Of course, the suppression of nonsignificant zeros in this column may also be inhibited by closing the switch associated with the column.

DOCUMENT FEED CONTROL DRIVER DRIVER DRIVER DRIVER PATENIED SEP 1 I97! SHEET 1 BF 4 FIG. lo

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ATTORNEY FIG.2

PATENIEDSEP nan 3.603.252

' sHEUunM COLUMN POSITION o b c d 0 f g h n swnnmaswosmou OLOSED oven I INPUTOATAOOOOO2OO o PRINT'OUT oo o 2 o o o ZERO SUPPRESSION CIRCUITS IN HIGH SPEED NUMERIC PRINTING BACKGROUND OF THE INVENTION This invention relates to high speed printers and, more particularly, to a circuit for selectively suppressing the printing of nonsignificant zeros by such a printer.

High speed printers are used to print the output information from data processing apparatus. Generally, these printers utilize a plurality of electrically operated print hammers aligned along the line being printed. Each hammer is associated with one of the columns in the line and prints characters therein by forcing the document being printed upon against selected type characters on a moving drum or chain located in back of the document.

The hammers are selectively operated to strike the type characters in response to coded electrical signals fed to the printer representing the characters to be printed. Usually, input signals representing an entire line of print are fed to the printer at one time. If no significant information is to be printed in certain columns, signals representing zeros are fed to those portions of the printers circuitry associated with these columns. Thus, if it were desired to print the number 538 with a printer having l columns, the signals fed to the print would represent 0000000538. The seven. zeros to the left of the number 5, although not significant, would be printed unless precautions were taken to prevent this. Such precautions generally take the form of an electrical circuit within the printer which suppresses the printing of nonsignificant zeros.

However, it may be desirable to have the characters printed in a format in which nonsignificant zeros are suppressed in certain columns while not in others. That is, certain columns will be within a zero suppression field while others will not be. Such a feature is desirable when printing on particular business forms or recording the results of certain scientific tests. Obviously, because of the myriad formats a printer may be called upon to print, it is desirable to be able to vary the location, extent,, and number of zero suppression fields in the line of print.

One example for which it may be desired to have some columns but not others within a zero suppression field may be found in recording a series of instrument readings. The data fed to the first or first few columns in each line may identify the particular reading to be recorded in that line. The desired format of the printout may require that the next few columns be left blank. Succeeding columns will contain the actual information obtained from the instrument readings. In those first columns which identify the reading being recorded, zero suppression may not be desired. Since no significant data is to be printed in those columns left blank, signals representing zeros are fed to the printer for these columns. These zeros, of course, are suppressed. A format may be desired which does not utilize zero suppression in those column within which the instrument readings are recorded. Thus, in this example, a zero suppression field is interposed between two groups of columns which do not contain zero suppression.

SUMMARY OF THE INVENTION In accordance with the invention, a zero suppression circuit is provided which allows the operator of a printer to easily vary zero suppression fields within the lines to be printed by closing selected switches.

The circuit comprises a plurality of print suppressing circuits, each of which is associated with one of the columns to be printed and, when actuated in response to signals indicating a nonsignificant zero, suppresses printing in its associated column. These print suppressing circuits are able to be selectively inhibited as desired by selectively actuating inhibiting circuits. The inhibiting circuits may be actuated, for example, by closing switches conveniently mounted on the back of the printers cabinet. In this manner, zero suppressing fields may be placed as desired within a line of print to produce any desired format.

Many of these formats may require a zero suppression field in the next least significant column after a column in which zero suppression has been inhibited. The circuit of the invention provides for this possibility with a plurality of coupling circuits, each of which is connected between two print suppressing circuits associated with adjacent columns. Each coupling circuit is also connected to the inhibiting circuit which is adapted to inhibit the print suppressing circuit associated with the more significant of the two adjacent columns. Each coupling circuit is actuated upon actuation of either this inhibiting circuit or the print suppressing circuit associated with the more significant column. When actuated, the coupling circuit conditions the print suppressing circuit associated with the less significant of the two adjacent columns so that this circuit may suppress the printing of zeros in its associated column. In this manner, a new zero suppression field is initiated.

BRIEF DESCRIPTION OF THE DRAWING FIGS. 1a, 1b, 1c, taken together, constitute a schematic diagram of a printer having a preferred embodiment of the zero suppressing circuit of the invention.

FIG. 2 is a table illustrating the operation of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. la, 1b and 1c together schematically show an on-thefly drum printer with its control circuit. In particular, F [0. 1b shows a rotating-type drum 1 having a plurality of numeric fonts located around its periphery in successive column locations, a through n. Identical characters in the fonts are aligned in a row parallel to the axis of the drum. The document being printed upon (not shown) is stepped line by line between the type drum and a bank of solenoid-operated hammers, 2a through 2n, each of which is located at a column along the drum. During a printing operation, each hammer is individually activated at the proper time to force the document against the type character which is to be printed in the column at which the hammer is located.

A code wheel 4 is mounted on the drums shaft to rotate therewith. The code wheel is shaped like a gear, each tooth of the gear corresponding to one row of type characters. When rotating, the code wheel 4 causes a magnetic transducer 5 mounted adjacent it to provide a series of positive timing pulses over lead 14, each timing pulse indicating the passing of one row of type characters past the hammers. The gearshaped code wheel has one of its teeth missing so that the magnetic transducer provides a series of positive indexing pulses over lead 15 when periodically sensing the missing tooth, each indexing pulse indicating a full drum revolution.

Before preceding with a description of the circuit in FIGS. la, lb and 1c, the means of the logic element symbols used therein is given. It is to be understood that the logic circuit elements operate, as is conventional, on a binary voltage level basis wherein the inputs to the elements and outputs therefrom always exist at either of two discreet voltage levels, the positive voltage level of the circuit or the negative voltage level of the circuit.

An AND circuit is represented by a D-shaped block containing an 61" symbol. The input lines are always connected to the straight side of the block and the output line is always connected to the curved side of the block. The function of this element is to provide a positive output voltage only when all input lines exist at the positive level.

An OR circuit is represented by an arrow-shaped block containing the symbol OR". Input lines are always connected to the concave side of the block and the output line is always connected to the point. The function of this circuit element is to provide a positive output only when any one or more of the input lines is at the positive level.

An inverter circuit is represented by a triangular block containing the symbol "I and having a small circle at the point where the output line joins the block. The function of this circuit element is to provide an output level which is always opposite to the input level.

A block labeled COUNTER represents a binary counter wherein a positive level signal at its input causes a binary number represented by coded signals on its output lines to advance by a count of l and wherein a positive signal at the reset input causes the output of the counter to revert to zero.

A block labeled FF represents a flip-flop circuit which is any type of bistable circuit arrangement wherein (assuming that the output is initially positive) a positive level signal at the T input causes the 1 output to go positive and stay positive while the 0 output simultaneously goes negative and stays negative. A succeeding positive level signal at the T input causes the 0 output to go positive and stay positive while the 1 output simultaneously goes negative and stays negative.

A block labeled COMP" in the drawing represents a comparator circuit which is any type of circuit wherein a positive level signal is provided at its output when coded signals applied to its inputs represent identical data.

A block labeled DRIVER" represents a driving circuit which is any type of circuit in which a positive level signal at its input causes an output of sufficient magnitude to operate an associated electrically opzrated element (in this case, a solenoid-operated print harm A block labeled ZERO DER is any type of circuit arrangement wherein a positiv levcl signal is provided at its output when the coded signals fed to its input represent a zero.

Referring now to FIG. la, signals representing the particular data to be printed are fed to a print storage circuit 6, in synchronism with suitable timing pulses T. The print storage circuit 6 stores the data to be printed in a single line of print. From the print storage circuit, data is fed via cables 7 to a plurality of buffer registers fizz-8n. Each buffer register is associated with a particular column and stores the character to be printed in its associated column for each line of print. From each buffer register, signals representing its stored character are fed to a zero decoder 9 and a comparator 10 (FIG. 1b). A plurality of zero decoders 9a9n and comparators l0a-10n are provided, each associated with that column with which the buffer register it receives data from is associated. The zero decoders 9a-9n provide positive outputs over leads Ila-lln when sensing signals representing zeros. Data is fed from the registers 8a-9n to the comparators l0a-10n over cables 2711-27 respectively.

Disregarding the operation of the zero suppression circuit for the present, as noted above, each buffer register 8 feeds signals over a cable 27 representing the character to be printed in its associated column to a comparator 10 associated with that column. As shown in FIG. lb, each comparator 10 also receives coded signals over a cable 29 from a counter 13 which has as its input the timing pulses on lead 14 from the transducer 5. The counters output signals represent the instantaneous positions of the characters on the rotating drum since its state advances by I each time a row of type characters passes the hammers. The index pulses from the transducer are transmitted over lead 15 to reset the counter to zero after each drum revolution.

When the inputs to a comparator 10 over cable 29 and one of the cables 27a-27n represent identical data, the drum in a position such that the particular type character to be printed in the comparator's associated column will be impacted by energizing a driver 3a-3n whose output operates the hammer associated with that column. At this time, the comparator provides a positive signal to one of a plurality of AND gates, 16a-16 n. Each AND gate 16 is associated with one of the columns, and when energized, feeds a positive signal to the driver 3 which operates the hammer 2 in its associated column. When energized, each driver 3 produces a short pulse of current sufficient to cause the solenoid-operated hammer 2 to move toward the print drum 1 and force the document against the type character to be printed.

The AND gates, 16a16n, all have an input connected to the 1 output of a flip-flop 17 which has as its T input the indexing pulses on lead 15 from the magnetic transducer 5. Each successive index pulse causes alternate outputs of the flip-flop to go positive. In this manner, the flip-flop 17 provides for two alternate discreet cycles of operation. In one cycle, when the flip-flops 1 output is positive, the AND gates 16 are conditioned to allow printing. In the other cycle, with the flip-flops 0 output positive, the document being printed upon is stepped by a feed control 18 to present another line to the hammers for printing.

Each of the AND gates 16 also has another input related to timing the operation of the printer. These inputs ofAND gates 7 1611-4611, are connected to the clock pulse lead 14 from the transducer 5 via an inverter 19. This allows the AND gates 16 to pass signals to the drivers 3 only between timing pulses. At these instants, the output signals from the counter 13 are not changing but are settled and steady.

Referring now to the preferred embodiment of the zero suppression circuit as illustrated in FIG. 1c, 21 print suppressing circuit 20 is associated with each column. Each print suppressing circuit 20 comprises an AND gate 21 and an inverter 22. Each AND gate 21 has an input connected over a lead 11 to the output of the zero decoder 9 associated with the column its print suppression circuit 20 is associated with. When an AND gate 21 is enabled it provides a positive signal to the inverter 22 within its print suppressing circuit 20. Each inverter 22 has its output connected over a lead 28a-28n to an input of one of the AND gates 16al6n (FIG. lb). Thus, when an AND gate 21 activates an inverter 22, its print suppressing circuit 2G is active to inhibit one of the AND gates 16a-16n and suppress printing in its associated column.

In suppressing nonsignificant zeros in the first column, Column a, any zero to be printed will be nonsignificant and thus should be suppressed. The AND gate 21a in the print suppressing circuit 20a associated with the first column, Column 0 has an input over lead 11a from the zero decoder 9a associated with the first column. When detecting a zero, the decoder 9a enables the AND gate 21a which actuates the inverter 22a to inhibit the AND gate over the lead 28a and, thereby suppress printing.

To suppress nonsignificant zeros in any column of less significance then Column a, the print suppressing circuit 20 associated with this column should be activated when a zero is to be printed in the column and a nonsignificant zero occurs in its next most significant column. The AND gate 21 in each of these print suppressing circuits has an input connected via an OR gate 23 to the output of the AND gate 21 in the print suppressing circuit 20 associated with the next most significant column. It, therefore, receives a conditioning input from an OR gate 23 when the AND gate 21 in the print suppressing circuit 20 associated with the next most significant column is energized and, thereby, indicates that a nonsignificant zero occurs in this next most significant column. Each of the AND gates 21 also receives an input over a lead 11 from the zero decoder associated with the same column its print suppressing circuit 20 is associated with. Thus, each suppressing circuit 20 associated with a column of less significance than Column a suppresses printing when its AND gate 21 receives a Zero-indicating positive signal over a lead 11 from the zero decoder associated with its respective column and also a positive signal via on OR gate 23 from the AND gate 21 in the print suppression circuit 20 associated with the next most significant column.

The zero suppression circuit also includes a plurality of inhibiting circuits, 24a24n, each of which is selectively operable to inhibit the AND gate 21 in a print suppressing circuit 20 and, thus, the print suppressing circuit itself. Each inhibiting circuit 24 comprises a selectively operable switch 25 and an inverter 26. Closing the switch 26 applies a positive potential V both to the input of the inverter 26 and to an input of the OR gate 23 which is connected between the print suppressing circuit 20 being inhibited and the one associated with the next least significant column. The inverter 26 has its output connected to an input of the AND gate 21 within the print suppressing circuit being inhibited', when the invert 26 is energized, the AND gate 21 is inhibited. in this manner, by merely closing the switches 25, the AND gates 21 and their print suppressing circuit 20 performing zero suppression may be int hibited. By selectively closing the switches 25, zero suppression in selected columns may be inhibited.

Each switch is connected to the input of an OR gate 23 in order to feed an enabling signal to the AND gate 21 in the print suppressing circuit 20 associated with the next least significant column. This enabling signal allows this print suppressing circuit to function as if a nonsignificant zero had occurred in its next most significant column and was suppressed. That is, the signal takes the place of the enabling signal from the AND gate 21 in the print suppressing circuit 20 associated with the next most significant column and, thereby allows zero suppression in the next least significant column. ,In this manner, a new zero suppression field is started in the next least significant column after a column in which zero suppression is inhibited. Of course, by closing the switch 25 at the column in which the new zero suppression field is to be initiated, the beginning of this new zero suppression field is passed on to the next lease significant column.

FIG. 2 illustrates, an example, a printout obtained by using the selective zero suppression circuit of FIG. 10. The switches 25 in Columns a and d through n are closed while those in Column b and c are open. Such a setup may be used when recording instrument readings in a format in which the data in Column a identifies the reading, Column b and c are blank, and Column d through n contain the actual numbers obtained by the readings. If a reading is identified in Column a as a zero, that zero is printed and so zero suppression in Column 0 is inhibited. Columns b and'c contain no significant data and thus the signals fed to the printer for these columns represent zeros. Since it is desired that Columns b and c be left blank zero suppression is used. Columns d through n contain the characters obtained by the instrument readings and zero suppression is not desired.

In the example illustrated in FIG. 2, the input data in Column (1 identifying the particular reading is a zero. Since Columns b and e do not contain significant data, the signals fed to the printer for these columns represent zeros. Columns (1 through It contain the actual instrument reading. Zeros occur in Columns d and e, a 2 occurs in Colunmfand zeros again in the columns thereafter.

Since Column 0 is the first column, any zeros therein are nonsignificant and, with zero suppression, would not be printed. Since it is desired to print the zero in Column 0, the switch 250 associated with this column is closed. This allows printing of the zero by activating the inverter 26a to inhibit the AND gate 21a in the print suppression circuit 20a associated with Column a. In this manner, the print'suppression circuit 20a is inhibited and printing of the zero allowed.

The switch 250, when closed, passes a signal through an OR gate 23 to the AND gate 21b in the print suppression circuit 20b associated with the next least significant column, i.e., Column b. This initiates a zero suppression field in Column b unless its associated switch 25b is closed. The switch 25b at Column b is open to allow zero suppression and the print suppressing circuit 20b associated with Column b is not inhibited.

. The AND gate 21b is enabled since it receives an enabling signal from the zero decoder 9b over lead llb indicating that a zero is to be printed and a positive signal via on OR gate 23 from the inhibit suppression circuit 24a associated with the next most significant column, i.e., Column a.

Column 0 is within the zero suppression field initiated at Column h. Since its switch 251' is open, printing of its zero is suppressed. The AND gate 21c in the print suppressing circuit 201. associated with Column 0 is enabled by signals front the zero decoder 9c and, via an OR gate 23, from the AND gate 21b in the print suppressing circuit associated with the next most significant column, Column b.

The switch 25d at Column d is closed to inhibit zero suppression in this column. This ends the zero suppression field of Columns b and c. The zero in the input data for Column d is printed. Similarly, the zero in Column e is printed.

A 2 is to be printed in Column fand, thus, the zero suppression circuit plays no part in its printout.

In Column 3, the zero to be printed is significant since it is in a less significant column than Column f in which a 2 was printed. Thus, irrespective of the position of the switch 25g at Column 3, the zero in Column g is printed. In the same manner as in Column g, zeros are printed in Columns h through n.

Iclaim: Y

1. In a high speed printer having a plurality of electrically operated print elements adapted to print numeric characters in successive columns of decreasing numeric significance, a circuit for selectively suppressing the printing of nonsignificant zeros comprising:

a. A plurality of circuits for suppressing printing, each of which is associated with one of the columns and adapted to inhibit the print element in that column;

b. a plurality of selectively actuatable circuits for inhibiting print suppression, each of which is connected to and adapted to inhibit one of the print suppressing circuits;

c. means for signalling each print suppressing circuit when a zero is to be printed in its associated column; and

d. means for connecting each print suppressing circuit with the print suppressing circuit associated with the next most significant column and the inhibit print suppression circuit adapted to inhibit the print suppressing circuit associated with the next most significant column, each print suppressing circuit being adapted to be actuated upon receiving a zero-indicating signal and a signal from either the print suppressing circuit associated with the next most significant column or the inhibit print suppression circuit adapted to inhibit the print suppressing circuit associated with the next most significant column.

2. The apparatus as recited in claim I wherein the connectingmeans comprises a plurality of coupling circuits, each of which is connected between the print suppressing circuits as sociated with two adjacent columns, each coupling circuit being adapted to be actuated either by the print suppressing circuit associated with the more significant olthc two columns orhy the inhibit print suppression circuit adapted to inhibit this print suppressing circuit, each print suppressing circuit bcing'adapted to be actuated upon actuation of the coupling circuit connected to the print suppressing circuit associated with the next most significant column and upon receiving a zero-indicating signal.

3. The apparatus as recited in claim 2 wherein the zerosignalling means comprises: means for detecting when a zero is to be printed in each column; and means for connecting the zero-detecting means to each print suppressing circuit.

4. A circuit for selectively suppressing the individual operations of a plurality of successive electrically operated elements, the circuit comprising:

a.'a plurality of successive suppressing circuits, each of which is associated with and adaptedto inhibit one of the electrically operated elements;

b. a plurality of selectively actuatable circuits for inhibiting suppression, each of which is connected to and adapted to inhibit one of the suppressing circuits; and

c. means for connecting each suppressing circuit with the suppressing circuit with precedes it and the inhibit suppression circuit adapted to inhibit this preceding suppressing circuit, each connecting means including a coupling circuit adapted to be actuated either by the preceding suppressing circuit or by the inhibit suppression circuit adapted to inhibit the preceding suppressing circuit, each suppressing circuit being adapted to be actuated upon actuation of the coupling circuit in the means connecting it to the preceding suppressing circuit and the inhibit suppression circuit adapted to inhibit the preced mg suppressing circuit. 

1. In a high speed printer having a plurality of electrically operated print elements adapted to print numeric characters in successive columns of decreasing numeric significance, a circuit for selectively suppressing the printing of nonsignificant zeros comprising: a. A plurality of circuits for suppressing printing, each of which is associated with one of the columns and adapted to inhibit the print element in that column; b. a plurality of selectively actuatable circuits for inhibiting print suppression, each of which is connected to and adapted to inhibit one of the print suppressing circuits; c. means for signalling each print suppressing circuit when a zero is to be printed in its associated column; and d. means for connecting each print suppressing circuit with the print suppressing circuit associated with the next most significant column and the inhibit print suppression circuit adapted to inhibit the print suppressing circuit associated with the next most significant column, each print suppressing circuit being adapted to be actuated upon receiving a zeroindicating signal and a signal from either the print suppressing circuit associated with the next most significant column or the inhibit print suppression circuit adapted to inhibit the print suppressing circuit associated with the next most significant column.
 2. The apparatus as recited in claim 1 wherein the connecting means comprises a plurality of coupling circuits, each of which is connected between the print suppressing circuits associated with two adjacent columns, each coupling circuit being adapted to be actuated either by the print suppressing circuit associated with the more significant of the two columns or by the inhibit print suppression circuit adapted to inhibit this print suppressing circuit, each print suppressing circuit being adapted to be actuated upon actuation of the coupling circuit connected to the print suppressing circuit associated with the next most significant column and upon receiving a zero-indicating signal.
 3. The apparatus as recited in claim 2 wherein the zero-signalling means comprises: means for detecting when a zero is to be printed in each column; and means for connecting the zero-detecting means to each print suppressing circuit.
 4. A circuit for selectively suppressing the individual operations of a plurality of successive electrically operated elements, the circuit comprising: a. a plurality of successive suppressing circuits, each of which is associated with and adapted to inhibit one of the electrically operated elements; b. a plurality of selectively actuatable circuits for inhibiting suppression, each of which is connected to and adapted to inhibit one of the suppressing circuits; and c. means for connecting each suppressing circuit with the suppressing circuit with precedes it and the inhibit suppression circuit adapted to inhibit this preceding suppressing circuit, each connecting means including a coupling circuit adapted to be actuated either by the preceding suppressing circuit or by the inhibit suppression circuit adapted to inhibit the preceding suppressing circuit, each suppressing cIrcuit being adapted to be actuated upon actuation of the coupling circuit in the means connecting it to the preceding suppressing circuit and the inhibit suppression circuit adapted to inhibit the preceding suppressing circuit. 